Process for manufacturing phenylthioglycolic acids containing halogen and alkyl groups in their molecule



Patented Nov. 17, 1931 rrao STATES PATENT OFFICE rennan HERZ, on rRnNKFoRr-oN-TnE-MA N, WILHELM BAUER, on wrn'siaonr/ NIEDERRHEIN, AND Non-BERT s'rnrenn, or nnAN nonr-oN-THn-MMN, GERMANY, ASSIGNORS 'ro GENERAL ANILINE WORKS, INC., on NEW YORK, N. Y, ACORPOBA- 'IION OF DELAWARE rnocnss non MANUFACTURING rHENYIirHIocLYooLro ACIDS CONTAINING HALOGEN AND ALKYL GROUPS IN THEIR MOLECULE' 7 No Drawing. Application filed. November 3, 1927, Serial No. 230,922, and in Germany November 24, 1926.

Phenylthioglyoolic acids, containing halogen and alkylgroups in their molecule, are

important intermediates for the production,

- of hydroxythionaphthene derivatives, containing halogen and alkylgroups in their molecule, and of the corresponding dyestuffs of the thioindigoandthionaphthenindolindigo type. They are hitherto mostly prepared from the corresponding aminohalogenalkylbenzenes by converting them into the xanthogenic esters according to Leukhardts reaction, saponifying the latter and condensing the mercaptan compounds thus obtained with monochloroacetic acid. This process is in many cases rather complicated and the products obtained by'it are often lacking in I yield and purity. Furthermore thestarting materials for this process are obtained by nitration and subsequent reduction of ,the

corresponding halogenalkylbenzenes. It is known, that the nitration process of these hydrocarbons yields in nearly all cases a-mixture of isomeric bodies, from which the desired products must be isolated by a tedious method. It is therefore a demand for a process which allows to manufacture these important phenylthioglycolic acids containing halogen and alkylgroups in their molecule by a techv it) nically simple method;

We have found such a process which consists in treating halogenalkylbenzenes With chlorosulfonicacid at temperatures below,

100, reducing the halogenalkylbenzenesulfochlorides thus formed to the correspondlng .mercaptan compounds and condensing the latter with monochloroacetic acid. In this manner phenylthioglycolic acids, containing halogen and alkylgroups in their molecule, are obtained with a very. satisfactory yield in an excellent state of purity. In contra'distinction to the nitratingprocess of halogenalkylbenzenes theintroduction of the" sulfochloride group into the molecule of these hydrocarbons runs almost uniformly. This is a surprising fact, because, as it is known, when subjecting toluene to the action of chlorosulfonic acid al'w ay's amixture of isomeric orthoandparacompounds is obtained. It should'be thereforeexpected,that- When subjecting instead of toluene halogenalkylbenzenes to the reaction also a mixture ofisomeric'sulfochlorides should be obtained. But apparently in these, halogenalkylbenzenes only the halogen has a directing influcues for thefentrance of the sulfochloride 55 group, locating it almost entirely into the para-position to one halogen. i

- Our present process gives particularly good results, when starting from benzenederiva (wherein X has the same signification) are obtained'in a very satisfactory yield and in an excellent state of purity.

In order to further illustrate our invention the following examples are.given,the parts being by weight and'alltemperatures in centigradedegrees, but we Wish to be u n-V der'stood that our invention is not limited to the examples given, nor-to the exact condi- At about 30-35" 8.1 parts of l-methyl-QA- n dichlorobenzene (boiling point 194) are slowly'introduced while stirring into 32 parts of chlorosulfonic acid. Then the mass is kept loo 7 for some hours at about 60 While stirring. After cooling down it is poured on ice and the reaction product separates in crystalline form.

The new l-methyl-QA-dichlorobenzene-5-sulfochloride thus formed melts in a pure state at 7 1.

\ Production of l-mthyl-Qdichlorobenzene-5-mercaptan of the formula:

aforesaid sulfochloride are lntro d uced into a mixture of about parts of sulfuric acid of 66 B, and 120 parts of I henzene-5-thioglycolic acid of the formula:

Hooomos- 19.3 parts of aforesaid mercaptan are dissolved in dilute caustic soda solution and "at ordinary temperature 10.7 parts, of monoch1oroaceticacid inform of itssodium salt are added. The 'mixtureis digest-ed, until a test does not show a yellow coloration with asolution oflead acetate. The 'l-methylQA 'dichlorobenz'ene-5-thioglycolic acid formed .may be'isolatedinform of the diflicultly soluble salts of sodium or calcium by adding common salt or chalk to the solution. or it may be separated as free acid by acidifying the cooled solution. In a pure state it melts at 112.

V Ebeamplz I (a) Productiongof IA-dimethyl-Q-chlorobenzene-5-sulfochloride of the formula: I CH3 7 CH3 v 'A about"ao ss fimre of LeHliinethyl-Q- "chlorobenzene (boiling point'192)" are slow 1y introduced into about 30 parts ofchloro;

sulfonic acid. Then the mass is kept for some hours at about 60 While stirring. After cooling down it is poured on ice and the L l-dimethyl-Q chlorobenzene-5-sulfochloride formed separates in a crystalline form. it is a new compound, unknown hitherto. It may be directly used for the further process.

If recrystallized from acetone it melts at 50.

(6) Production of 1.4 di1nethyl-2-chlor0- benzene-5-1nercaptan of the formula V 24 parts of the aforesaid sulfochloride compound are introduced nto a mixture of about 55parts of sulfuric acid of 66 1%. and

I 120 partsof water and slowlyabout 30 parts of zinc dust are adder. While stirring; the mass-is kept for some time advantageously at The reductionprocess runs smoothly and after 'coolingldown the l-dimethyi-Q- chlorobenzene-5-mercapta-n separates as crystalline mass; it is isolated by filtration and can be directly used for the production of thethioglycolio compound. In order to obtain it in a pure state it may be subjected to a'steam distillation."

Production of 1.4-dimethyl-2chlorobenzene-thioglycolic acid of the formula:

17 .8'parts of the aforesaid mercaptan are dissolved in "dilute caustic soda solution and at ordinary temperature 10.7 parts of monochloroacetic acid inform of its sodium salt are added. TN hen the reaction is complete, the 1.4-diniethyl2-chloroben zene-5-thioglycolic acid formedmay be isolated in form of its-diflicultly soluble salts or as free acid by acidifying'the solution. In a pure state it melts at 9691 When starting from l.4-dimethyl-2-bro1nobenzene in the same manner the'lA-dimethyl- 2 bromobenzene-5-thioglycolic acid can be obtained.

:lVe claim alkylgroups in their molecule, Which process comprises treating halogenalkylbenzenes with chlorosulfonic acid at temperatures ber low reducing the halogenalkylbenzenesulfochlorides thus formed to the correspondingmercaptan compounds and condensing the latter with monochloroacetl-c' acld.

1 3-1. A- process "for manufacturing phenyltlllOfllYCOllC aclds containing halogen and 2. A process formanufacturing phenylthioglycolic acidsof the general formula:

Hal

HOOCHzCS- in which formula X means halogen or CH which process comprises treating benzenederlvatlves of the formula:

Hal

, in which formula X has the aforesaid signification, with chlorosulfonic acid at teIn: I

peratures below 100, reducing the halogenalkylbenzenesulfochlorides thus formed to HOOCHICS- inwhich formula X means chlorine or CH which process comprises treating benzene derlvatives of'the formula: 7

' in which formula X has the aforesaid signification with chlorosulfonic acid at temperatures below 100, reducing the chloromethylbenzenesulfochlorides thus formed to the corresponding mercaptan compounds and condensing the latter with monochloro- 1 acetic acid.

4. As new compounds phenylsulfochlorides of the formula: i

in which formula X means chlorine or CH 7 I of the general formula with products-obtainable by treatingbenzenederiyatives of the formula:

in which formula X has the aforesaid significationywith chlorosulfonic acid at temperatures below 100.

chlorobenzene-5-sulfochloride of the 'formula:.

melting in a pure state at being substani tially identical with a product obtainable by treating 1.4-dimethyl-2-chlorobenzene with chlorosulfonic acid at temperatures below 100. 3. A process for manufacturing phenyl- 6. The process of manufacturing phenylsulfochlorides of the general formula:

Hal

' OLOzS wherein X represents halogen or methyl which process comprises treating a compound of the general formula:

wherein X represents halogen or methyl,

f 5. As a new compound 1.4-dimethyl-2- with chlorosulfonic acid at a temperature Y below 100 C.

' 7. The process of manufacturing phenylsulfochlorides of the general formula:

wherein X' represents chlorine or methyl which process comprises treating a compound which compounds are when dry crystalline powders, having a definite melting point, which compounds-are substantially identical natures wlrereiu X r'epres euts chlorine or methyl,

ing the resulting 1.4-c1imethy1-2-ch1orobenzene 5 -sulfochlorider 4 1 v In testimony whereof, We aflix our Sig- RICHARD'HE R ZQ I NORBERT STEIGER.

In testimony whereof, I a-ffiX my signature. WILHELM BAUER 

